Human visual event-related potentials (ERPs) and the electroencephalogram (EEG) measure a variety of different cognitive operations during visual processing. Visual ERPs and EEG are vital tools in diagnosing and studying neurological and psychopathological disorders, in addition to revealing how the health brain turns visual inputs into appropriate responses. However, it is not possible to definitively determine what brain areas generate specific ERP components and EEG oscillations related to deploying visual attention, visual working memory storage, and monitoring task performance. The renewal of this project will support our work localizing the sources of ERP components and oscillatory signatures elicited during the performance of visual tasks using both humans and nonhuman primates. In the latter we will record noninvasive ERPs and EEG simultaneously with intracranial recordings of local field potentials. Preliminary evidence from monkeys and humans performing identical visual tasks demonstrates homology between human and macaque ERP components and the modulation of specific frequency bands in the EEG providing indices of the deployment of visual attention, the storage of visual information in visual working memory, and performance monitoring. By concurrently studying humans and monkeys this project will allow clinicians and health researchers to use the visually and response evoked EEG activity and ERP components recorded noninvasively from humans to access whether specific brain regions are functioning properly and also to develop animal models of specific disorders. Relevance to public health: The overall goal of this research program is to perform comparative studies of humans and monkeys using common electrophysiological measures. Then, to develop techniques to determine whether nonhuman primates exhibit electrophysiological oscillations and event-related potentials indexing the same cognitive processes as those used to study mental and other health disorders in humans. Our previous work demonstrates that these common electrophysiological measures exist and the present project will use humans and monkeys to determine where in the brain these potentials are generated. These methods will provide a way for health researchers to develop animal models of human health disorders, discover underlying causes, and test potential treatments.